This study investigates the source of second language (L2) learners' low use of conventional expressions--one part of pragmalinguistic competence--by investigating the relationship between recognition and production of conventional expressions in L2 pragmatics. Two tasks--an aural recognition task and an oral production task--were completed by 122 learners of English as a second language with mixed-language backgrounds and 49 native speakers of English divided among peers and teachers. The aural recognition task presented 60 expressions to which participants responded with one of three levels of self-assessed familiarity, operationalized as an estimate of how often they hear a given expression ("I often/sometimes/never hear this"). The computer-delivered production task included 32 scenarios to which participants responded orally. Results show that recognition of conventional expressions is a necessary condition for production but not sufficient. Lower use of conventional expressions by learners may have multiple sources: lack of familiarity with some expressions; overuse of familiar expressions, which subsequently reduces the opportunity to use more targetlike expressions; level of development; and sociopragmatic knowledge.